Peroxidase enzymes such as horseradish peroxidase (HRP) are frequently used as markers or labels in enzyme-linked assays for biological molecules and other analytes of interest such as drugs, hormones, steroids and cancer markers. Chemiluminescent detection of these enzymes offers a safe, convenient and sensitive means to provide a quantitative measure of the amount of enzyme in a sample or of the amount of an enzyme-labeled analyte or labeled specific binding partner for an analyte. Other chemiluminescent reaction schemes have been developed to quantitate the level of particular peroxidase enzymes.